Synchronous reluctance machines and interior permanent magnet machines may be particularly well suited for use in propulsion (e.g., any force or thrust gained through a fluid medium) devices for aircrafts, as well as for use as a powerplant in traction devices (e.g., road or railway vehicles) and marine devices (e.g., ships).
Depending on a magnitude, torque “ripple”, or torque oscillations, of the above electric machines, may result in damage to a rotor and/or the mechanical system(s) connected to the electric machines (due to fatigue or excessive torque). Additionally, the frequency of the torque ripple might excite resonant modes of the mechanical system(s), posing an additional threat to the above electric machines and/or surrounding systems.
Various attempts at reducing torque ripple have been researched. These attempts generally include either a stator based design, or a rotor based design. The stator based designs typically include stator slot width optimization, stator tooth pairing, stator tooth notching, odd slot numbers, stator tooth shifting, or stator skewing. The rotor based designs include rotor pole width optimization, magnet shaping, magnet pole shifting, rotor pole pairing, magnetization pattern, magnet segmentation, or rotor skewing. All those approaches inevitably lead to some degree of compromise in an overall performance of the machine and have their own limitations.
Accordingly, there is an ongoing need for improving on current electric machine technologies and/or manufacturing thereof that address at least one of complexity, cost, efficiency, and/or performance without some of the current tradeoffs encountered with current methodologies.